A shared pleiotropy of bone and muscle mass: muscle mass is more strongly associated with bone mass than with fat mass or deterioration of glucose metabolism in the elderly

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 199-233-Bone Biology
Basic/Clinical
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-216
Kyeong Hye Park*1, Kyoung Min Kim2, Jo Eun Kim1, Yumie Rhee1 and Sung-Kil Lim1
1Yonsei University College of Medicine, Seoul, South Korea, 2Bundang Seoul National University Hospital, South Korea
Introduction

There is a clear evidence of genetic pleiotropy between the muscle and the bone. These two different tissues may share the same aging process through same genetic determinants and show different manifestations, sarcopenia and osteoporosis. Also, there are evidences supporting that the muscle is an endocrine organ, stemming from the its regulation of glucose metabolism. The aim of this study is to determine the influence of muscle mass on the bone, fat and glucose metabolism profiles.

Methods

We studied 1,578 people aged more than 65 years old who had participated in the Fourth Korean National Health and Nutrition Examination Surveys IV (2008-2009). Age-related change of muscle mass was analyzed by dividing the subjects into 5-year interval in both gender. Those whose muscle mass were lower than one standard deviation from the peak muscle mass were allocated into the low muscle mass group, and the others were classified as the control group. Subgroup analysis of the low muscle mass group by classifing them into three groups based on their total body fat mass percentage was performed. Bone mass and glucose metabolic profiles (fasting blood glucose, HbA1C, and HOMA-IR) were also analyzed.

Result

The peak muscle mass accrual in the Korean population was obtained at age of 20-25 years in men and 55-60 years in women. Bone mass in lumbar spine (LS), femur neck (FN) and total hip (TH) were highly correlated with muscle mass in both gender (p value <0.01). This correlation was higher in cortical bone area(FN or TH) than trabecular bone area(LS). The low muscle mass group showed lower bone mass than the control group. However, there was no association between muscle and fat mass, and no differences in fat mass between the low muscle group and control group were observed. These findings implied greater bone-muscle interaction compared to bone-fat interaction.

Muscle mass and glucose metabolic profiles did not show any correlation. Furthermore, insulin resistance was not higher but lower in the low muscle group than the control group, contrary to previous evidences showing that low muscle mass deteriorates glucose metabolism.

A subgroup analysis of the low muscle mass group showed that increased fat mass led to greater insulin resistance. However, bone mass increased in association with increases in fat mass: this seemed to be the result of weight-bearing effect, and did not reflect a positive effect of fat mass on bone mass.

Conclusion

Ages reaching the peak muscle mass, as well as the extent and the speed of muscle loss differed between the genders. Ethnic factors and environmental factors, such as lifestyle, may have caused the difference. Muscle mass was strongly associated with bone mass in the elderly population. Furthermore, subjects with lower muscle mass and higher fat mass were vulnerable to insulin resistance. The muscle and the bone may proceed in the same direction with respect to the aging.

Nothing to Disclose: KHP, KMK, JEK, YR, SKL

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm